Easy Mexican Pork Burritos

INGREDIENTS

• 3 pounds bone-in pork shoulder roast
• 1 onion, sliced
• 6 cloves garlic, chopped
• 1 (1.25 ounce) package taco seasoning mix
• 6 cups water, or as needed to cover
• 1 (14.5 ounce) can diced tomatoes
• 1 (16 ounce) can refried beans
• 1 (4 ounce) can chopped green chiles, or to taste
• 1 (16 ounce) package shredded Cheddar cheese
• 20 (10 inch) flour tortillas
• 1/4 cup vegetable oil, divided